The use of hydraulic attachments on motorized vehicles is common. Two well known examples are road graders and snow ploughs. For clarity, the term “hydraulic attachment”, as used herein, refers to—for example—the plough on a snow plough, or the blade on a grader, or the tree spade, elements on a motorized tree spade. The motorized vehicle contains a motor or engine (such as a gasoline or diesel engine) that drives the vehicle and also provides energy to a hydraulic pump which drives the hydraulic attachments.
Several types of control systems for the hydraulically driven components are in widespread use, as briefly outlined below.
A “manual over hydraulic” control may be appropriate for a hydraulic attachment with a limited range of functions. In one simple system, a single hydraulic valve is located on the power unit (or pump), and this valve provides on/off control for an attachment that is connected to the valve by way of a single pair of hydraulic lines.
The use of a control system with multiple hydraulic valves that may be manually operated provides additional flexibility for slightly more complicated hydraulically driven attachments.
For more complicated hydraulic components, the use of an “electric over hydraulic” control system is often employed, especially when the hydraulically driven attachment has five or more separate features. A typical electric over hydraulic control system would include a plurality of hydraulic lines, a plurality of valves to control the flow to the hydraulic lines, and an actuation system for the valves that responds to an electric signal. The use of well known solenoid valves is commonly employed. One advantage of the electric over hydraulic control is that it allows for a great deal of design flexibility. In general, another “feature” of the hydraulic system may be readily added by adding another solenoid valve set, hydraulic lines and wire. However as the number of features increases, the number of electric wires also increases. It is not uncommon to have more than a dozen wires in a control cable for a complicated hydraulic system—such as the hydraulic system for a tree spade or other nursery equipment such as tree moving and handling equipment. This control cable is often subject to a considerable amount of abuse during the normal operation of the machinery. Problems arise when the wires become disconnected, or when the cable is pinched, and or pulled apart. Repair of the system can be particularly time consuming if the problem is intermittent (as may be caused by a loose connection) or when attempting to repair a single wire in the cable (which requires that the wire be correctly identified) or even when replacing the whole cable (which requires that all of the new wires are properly re-connected). Accordingly, a need exists for a hydraulic control system that is robust enough to face heavy use and which may be quickly replaced when failure occurs.
Furthermore, a conventional, wired, electric over hydraulic control system requires two sets of hookups between the motorized vehicle and the hydraulic tool—namely the hydraulic hook up system and the electric hook up system. Many operators of motorized/hydraulic equipment will use more than one type of tool with the motorized vehicle.
For example, a nursery operator may have one tool to dig trees (a “tree spade”), another tool to wrap the trees and a third tool to move large potted plants and trees.
One operator error that sometimes occurs when changing hydraulic attachments is that the hydraulic lines are properly disconnected but the electric cable is not. Thus, when the vehicle attempts to drive away from the particular detached tool, the electrical hook up is torn apart.
The use of wireless control systems in motorized/hydraulic equipment is contemplated in U.S. Pat. No. 4,776,750 (Griswold). However the wireless system that is contemplated by Griswold et al. is not a wireless control system that is powered by electricity from a generator driven by hydraulic fluid.
U.S. Pat. No. 6,510,902 (Prokop) describes a hydraulically driven rock fracturing machine. The Prokop machine has an electronic data acquisition system that monitors the use of the machine. This data acquisition system may be powered by electricity that is generated from a generator that is powered by hydraulic fluid; however, the data acquisition system of Prokop is not an electric over hydraulic control system that controls a hydraulic attachment based on an input signal from an operator.